In Generations 3 - 6, there are 11 unobtainable shiny Legendary Pokemon.
(Well, if that's what you were trying to ask, anyways...)

These include:Arceus (Event Pokemon)Celebi (Event Pokemon)Victini (Coded not to be Shiny in Black/White Games)Reshiram (Coded not to be shiny in Black/White/B2/W2 games)Zekrom (Coded not to be shiny in Black/White/B2/W2 games)Keldeo (Event Pokemon)Meloetta (Event Pokemon)Xerneas (Coded not to be shiny in X and Y)Yvetal (Coded not to be shiny in X and Y)Zygarde (Coded not to be shiny in X and Y)Diancie (Event Pokemon)